Keep in mind that if the card is actually a 1542, instead of a 1540, then it also has a floppy controller on board which might conflict with the motherboard or I/O Card floppy controller. I think it can be easily disabled by using the ctrl-A option at boot time to enter the Adaptec utilities where the option to disable the floppy controller is available.

Windows XP is a mystery to me, but I knew the hardware world of 3.1 and '95. Kind of like, 68K and PPC I understand but drag me into OSX and I'm (mostly) lost.